Dresden 2020 – wissenschaftliches Programm
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DY 3.9: Vortrag
Montag, 16. März 2020, 12:00–12:15, ZEU 118
On the Inertial Range Scaling at Extreme Reyolds Numbers — •Christian Küchler1,3, Gregory P. Bewley2, and Eberhard Bodenschatz1,2,3 — 1Max-Planck-Institute for Dynamics and Self-Organization, Göttingen — 2Cornell University, Ithaca, NY, USA — 3Georg August University Göttingen
Kolmogorov predicted in 1941 that universal scaling laws emerge in the increment statistics of turbulent velocities in the limit of infinite Reynolds numbers. In the past it has been found that this limit - if existent - requires extreme Reynolds numbers, which are difficult and expensive to create in a well-controlled turbulent flow. The Variable Density Turbulence Tunnel (Bodenschatz et al., 2014) is the first wind tunnel capable of producing such extreme Reynolds numbers finally allowing us to systematically study the long-standing Kolmogorov prediction and its refinements. The experiment combines the low kinematic viscosity of pressurized SF6 and an active grid with individually controllable tiles (Griffin et al., 2019). With Nanoscale Thermal Anemometry Probes developed and generously provided by Princeton University (e.g. Bailey et al. (2009), Vallikivi et al. (2014)) we adequately resolve the small scale turbulence. We present results that logarithmic derivatives of structure functions differ from conventional scaling laws of isotropic turbulence. However, these local scaling exponents approach a universal form at some critical Reynolds number. We show that those results are well-described by the generalized self-similar spectrum of decaying turbulence introduced by Yang et al. (2018). It further allows us to extract the scaling exponent.